Signal processor based MSAT trellis coded M-DPSK with adaptive Doppler phasor correction
Abstract
A trellis coded M-differential phase shift keying (DPSK) modem with convolutional interleaving and deinterleaving has been developed and tested on a system consisting of three signal processing chips. The coded modem is either 2400 or 4800 bps in a 5 kHz bandwidth, whereas 1200 to 7200 bps can be supported without coding. All digital transmitters and receivers are designed using a 4 kHz carrier. Integrate and dump driven Viterbi decoding is used. Timing recovery is based on early/late gate principles which are extended to 8-DPSK modulation. This involves a novel threshold scheme. Open-loop Doppler correction is used in the setup mode and the tracking technique of Ungerboeck, Edbauer, and Natali (1982, 1989, 1986) for the data mode. The Doppler phasor is corrected rather than the Doppler frequency as it is easier to implement in digital signal processing realizations. The modem has been tested in the laboratory for a noise channel and no Doppler frequency correction.
- Publication:
-
Electrical and Computer Engineering, Volumes 1 and 2 4 p (SEE N93-30215 11-31)
- Pub Date:
- 1990
- Bibcode:
- 1990ecev.confX....B
- Keywords:
-
- Modems;
- Phase Shift Keying;
- Satellite Communication;
- Signal Processing;
- Trellis Coding;
- Algorithms;
- Doppler Effect;
- Frequency Control;
- Mobile Communication Systems;
- Viterbi Decoders;
- Communications and Radar